Foot loading is different in people with and without pincer nails: a case control study

Abstract

BackgroundRecent studies suggest that pincer nails are caused by lack of upward mechanical forces on the toe pad. However, clinically significant pincer nails are also often observed among healthy walkers. It was hypothesized that in these cases, the affected toes do not receive adequate physical stimulation from walking and loading. To test this, the gait characteristics of pincer nail cases were assessed by measuring plantar pressure during walking.MethodsIn total, 12 bilateral pincer nail cases (24 affected feet) and 12 age- and sex-controlled healthy control subjects (24 ft) were enrolled in this prospective case–control study. Plantar pressure during free ambulation in both the barefoot and shod state was assessed using a digital pressure-plate system named S-Plate platform (Medicapteurs Co. France). First toe pressure and the frequencies of peak pressure in the first toe, metatarsal head, or other foot areas were calculated.ResultsIn both the barefoot and shod state, the pincer nail group had significantly lower pressure on the first toe than the control group. In both the barefoot and shod state, the peak pressure area was mostly the metatarsal head area in the pincer nail group, whereas it was mostly the first toe area in the control group. Binomial logistic regression analysis revealed that peak pressure area was a significant risk factor for pincer nail development.ConclusionWalking behavior appears to contribute to pincer nail development. Pincer nails of walkers could be treated by correcting the walking behaviour so that more pressure is placed on the toe pad.

Presence of a family history and excessive pressure on the first toe pad during walking in female subjects with pincer nails

“…This may explain why athletes who need to kick the ground strongly frequently experience PN . However, our data conflict with previous reports wherein authors have demonstrated that the pressure on the first toe of subjects with PN was lower than that of those without PN, and that subjects with PN experienced peak pressure on the metatarsal area . This discrepancy may be attributable to the fact that we only studied female subjects with PN and used different devices for analyses.…”

“…The first toe nail of bedridden individuals is known to show more overcurvature than that of healthy individuals, suggesting that a lack of upward mechanical forces cause PN . Additionally, an analysis of the pressure on the first toe of healthy individuals with PN showed lower pressure than that of those without PN . Moreover, healthy individuals with PN experienced peak pressure on the metatarsal area, while those without PN experienced it on the first toe area .…”

“…2 Additionally, an analysis of the pressure on the first toe of healthy individuals with PN showed lower pressure than that of those without PN. 3 Moreover, healthy individuals with PN experienced peak pressure on the metatarsal area, while those without PN experienced it on the first toe area. 3 Based on these observations, similar to that in bedridden individuals, a lack of upward mechanical force on the first toe appears to cause PN in healthy individuals.…”

“…3 Moreover, healthy individuals with PN experienced peak pressure on the metatarsal area, while those without PN experienced it on the first toe area. 3 Based on these observations, similar to that in bedridden individuals, a lack of upward mechanical force on the first toe appears to cause PN in healthy individuals. 4 In order to observe the detailed gait motion of healthy individuals with PN, we developed a novel wireless device and analyzed the pressures on the first and fifth toes, both the pad (on the distal phalanx) and the ball (on the metatarsophalangeal joint), and tracked the gravity center during walking.…”

Preservative and surgical interventions to treat ingrown nail and pincer nail

“…A force from the downward usually works to flatten nail plate, and lack of such a force causes pincer nail. Sano et al have reported that in both the barefoot and the shod state, the patient group of pincer nail had significantly lower pressure on the first toe than the control group. Loss of pressure could contribute to the development of pincer nail.…”